package chapter6;

import java.io.OutputStreamWriter;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.Provider;
import java.security.Security;
import java.security.cert.X509Certificate;
import java.util.Date;
import java.util.Enumeration;

import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Set;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.pkcs.Attribute;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.asn1.x509.BasicConstraints;
import org.bouncycastle.asn1.x509.ExtendedKeyUsage;
import org.bouncycastle.asn1.x509.KeyPurposeId;
import org.bouncycastle.asn1.x509.KeyUsage;
import org.bouncycastle.asn1.x509.X509Extension;
import org.bouncycastle.asn1.x509.X509Extensions;
import org.bouncycastle.jce.PKCS10CertificationRequest;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMWriter;
import org.bouncycastle.openssl.jcajce.JcaPEMWriter;
import org.bouncycastle.x509.X509V3CertificateGenerator;
import org.bouncycastle.x509.extension.AuthorityKeyIdentifierStructure;
import sun.security.jca.Providers;

/**
 * An example of a basic CA.
 */
public class PKCS10CertCreateExample {
    public static X509Certificate[] buildChain() throws Exception {
        // create the certification request
        KeyPair pair = Utils.generateRSAKeyPair();

        PKCS10CertificationRequest request = PKCS10ExtensionExample.generateRequest(pair);

        // create a root certificate
        KeyPair rootPair = Utils.generateRSAKeyPair();
        X509Certificate rootCert = X509V1CreateExample.generateV1Certificate(rootPair);

        // validate the certification request
        if (!request.verify("BC")) {
            System.out.println("request failed to verify!");
            System.exit(1);
        }

        // create the certificate using the information in the request
        X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();

        certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
        certGen.setIssuerDN(rootCert.getSubjectX500Principal());
        certGen.setNotBefore(new Date(System.currentTimeMillis()));
        certGen.setNotAfter(new Date(System.currentTimeMillis() + 50000));
        //certGen.setSubjectDN(request.getCertificationRequestInfo().getSubject());
        certGen.setPublicKey(request.getPublicKey("BC"));
        certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");

        certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, false, new AuthorityKeyIdentifierStructure(rootCert));

        // certGen.addExtension(X509Extensions.SubjectKeyIdentifier, false, new SubjectKeyIdentifierStructure(request.getPublicKey("BC")));

        certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false));

        certGen.addExtension(X509Extensions.KeyUsage, true, new KeyUsage(KeyUsage.digitalSignature | KeyUsage.keyEncipherment));

        certGen.addExtension(X509Extensions.ExtendedKeyUsage, true, new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth));

        // extract the extension request attribute
        ASN1Set attributes = request.getCertificationRequestInfo().getAttributes();

        for (int i = 0; i != attributes.size(); i++) {
            Attribute attr = Attribute.getInstance(attributes.getObjectAt(i));

            // process extension request
            if (attr.getAttrType().equals(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest)) {
                X509Extensions extensions = X509Extensions.getInstance(attr.getAttrValues().getObjectAt(0));

                Enumeration e = extensions.oids();
                while (e.hasMoreElements()) {
                    DERObjectIdentifier oid = (DERObjectIdentifier) e.nextElement();
                    X509Extension ext = extensions.getExtension(oid);

                    certGen.addExtension(oid, ext.isCritical(), ext.getValue().getOctets());
                }
            }
        }

        X509Certificate issuedCert = certGen.generateX509Certificate(rootPair.getPrivate());

        return new X509Certificate[]{issuedCert, rootCert};
    }

    public static void main(
            String[] args)
            throws Exception {
        // bouncycastle

        Security.addProvider(new BouncyCastleProvider());


        X509Certificate[] chain = buildChain();
        PEMWriter pemWrt = new PEMWriter(new OutputStreamWriter(System.out));

        pemWrt.writeObject(chain[0]);
        pemWrt.writeObject(chain[1]);

        pemWrt.close();
    }
}